Comments from reviewing the new video merge

[Elrond]

In this bug I will put comments as I review the new video code. I
will add new comments to this ticket as I go. I hope this is okay
and will be workable.

[Elrond]

1) setup.py: don't depend on "gst". I think, it was decided, that
   optional packages have to be installed by users using virtualenv.
2) ``mediagoblin/views.py``: Why does it import ``media_types``?
3) ``mediagoblin/views.py``: Why does it import ``sys`` and give it
   to root.html?

[Christopher Allan Webber]

I commented out the requires='gst' till we find out from joar why
it's there.

[Elrond]

4) ``mediagoblin/media_types/video/transcoders.py``:
   ``VideoThumbnailer.errors`` is a class level variable, so it is
   shared between all instances. I don't think, thit is, what you
   want. initialize it in ``__init__``.
5) ``mediagoblin/media_types/image/processing.py``: Are all those
   celery imports needed?
6) ``get_media_manager(_media_type = None)``: Why the default
   argument? I think, the function will fail with the default
   argument.

[Elrond]

7) If one doesn't have pygst installed, unit tests fail.

[joar]

https://github.com/jwandborg/mediagoblin/tree/b681-comments\_from\_reviewing\_video

Everything fixed except the pygst unit test issue.

[joar]

Haven't solved the failing tests yet, assigning it for feedback
meanwhile.

[Elrond]

Great!
Merged!

Leaves us with point 7).

The problem is basicly that nose imports every .py file it finds on
its way to search for unit tests in that .py file. And just
importing the file breaks.

One option would be to somehow (I have no idea how) tell nose to
search for tests only in ``mediagoblin.tests``.
Another option would be for the failing file (I can dig details up)
to check if video is enabled, and if not, cancel the parsing early
and get out (no idea either on how to do that sys.exit is not a
good idea, I guess.

[Will Kahn-Greene]

The original url for this bug was ​http://bugs.foocorp.net/issues/681 .

[Elrond]

The final remaining point "7)" is covered in its own ticket: #355

So let's close this one as "all points done, or at least delegated".

(hinted by ShawnRisk)